When you do a mule drop in order to repair a mech, can you click on the mechanical unit itself while doing the drop, or do you have to wait for the mule to appear, and then order it to repair?
I tested this in a custom game vs an AI opponent.
You cannot click on the mech unit with the MULE target. You must click on the ground beside the unit to drop the MULE, select the MULE, then right click on the target to start repairing it.
You must turn on auto-repair for it to automatically start repairing other nearby mech units.